(1) Field of the Invention
The present invention relates to a method for ensiling silage and in particular high moisture corn using a unique strain Propionibacterium acidipropionici DH42 alone or in admixture with lactic acid bacteria. In particular, the present invention relates to a method which produces improved nutrient values in ensiling and when the silage is exposed to aerobic conditions upon removal from the silo.
(2) Description of Related Art
Aerobic deterioration of ensiled feeds is detrimental to the production of livestock feeds for many reasons (Muck, R. E., J. Dairy Sci. 71:2992 (1988); is and Pitt, R. E., Silage and Hay Preservation. Ithaca, N.Y. Northeast Regional Engineering Service NRAES-5 (1990)). Aerobic microorganisms such as yeasts, molds and certain bacteria metabolize the highly-digestible fraction of the dry matter and can account for losses of dry matter in excess of 30% (Woolford, M. K., J. Appl. Bacteriol. 68:101 (1990)). In addition, microbial activity associated with aerobic deterioration can increase the temperature of the feed and generate feed that is less palatable and reduced digestibility (Ruxton, G. D., et al., J. Sci. Food Agric. 62:209 (1993)). Propionic acid has been used quite successfully in reducing losses associated with aerobic instability (Lindgren, S., et al., J. Sci. Food Agric. 36:765 (1985)). Flores-Galarza and coworkers (Flores-Galarza, R., et al., J. Food Prot. 48:467 (1985)) added strains of propionic acid-producing bacteria commonly found in cheese and decreased proliferation of yeasts and molds associated with high-moisture corn. However, Lindgren and coworkers (Lindgren, S., et al., Swed. J. Of Agric. Res. 13:91 (1983)) were unsuccessful in manipulating the fermentation of grass silage by the addition of P. shermanii.
In recent years, ensiling high moisture corn (HMC) has gained wide acceptance for several reasons. Ensiling eliminates the added cost of drying and the corn can be harvested two (2) to three (3) weeks earlier, thereby reducing field losses. If corn is harvested at 24-30% moisture content, dry matter loss can be reduced by 3-8% (Huber, J. T., Anim. Nutr. Health 34:6-8 (1982)). If properly stored, high moisture corn has the same feeding value, if not better, than dry corn (Hellevang and Morey, Energy Conservation and Alternative Energy Source for Corn Dyring. Nat. Corn Hand. Cooperative Extension Service 1985). However, if high moisture corn is not properly ensiled, spoilage due to microbial metabolism could occur.
Silage additives such as bacterial inoculants, acids and enzymes have been developed to improve fermentation and reduce spoilage. With the addition of lactic acid-producing bacterial inoculants, lactic acid concentration and dry matter recovery are increased. However, the stability of the ensiled material once the silos are opened has been inconsistent (Rust, S. R., et al., J. Prod. Agric. 2:235-241 (1989); Phillip, L. E., et al., J. Anim. Sci. 70:3178-3187 (1992); Sanderson, M. A., J. Anim. Sci. 71:505-514 (1993); Wardynski et al, J. Anim. Sci. 71:2246 (1993)).
Thus the prior art has described the use of various species of Lactobacillus and/or Propionibacterium to ensile various plant materials, particularly corn. Illustrative is U.S. Pat. No. 4,981,705 to Tomes; Dawson et al Abstract 21st Biennial Conference on Rumen Function, Chicago, Ill. (1991); Woolford et al, J. Applied Bact. 39:301-306 (1975) and Flores-Galarza, J. Food Protection 48:407-411 (1985).
Studies on the use of propionic acid have shown it to be an effective mold inhibitor. Propionic acid also increased storage life of high-moisture grain (Jones, G. M., et al, Can. J. Anim. Sci. 54:499 (1974)), decreased soluble protein loss, and improved aerobic stability (Woolford, M. K., et al., Proc. 13th International Grassland Congr. Leipzig (1977); Britt, D. G., et al, J. Dairy Sci. 58:532 (1975); Hara, S., et al., Jap. J. Zootech. Sci. 50:288 (1979); Raeker et al in Cereal Chemistry 69(1):66-69 (1992) and by Woskow et al, Applied and Environmental Microbiology 57:2821-2828 (1991)).
U.S. Pat. No. 5,534,271 to Ware et al and U.S. Pat. No. 5,529,793 to Garner et al describe direct feeding without ensiling. It is believed that ensiling produces better results.
There is still a need for an improved propionibacterium for ensiling silage and in particular high moisture corn.